The effects of urbanization on chemical characteristics of forest soil in Tamagawa basin, Japan

In order to clarify the effects of urbanization on the chemical characteristics of forest soils, we investigated several surface soil chemical characteristics, including (1) carbon (C) concentration, (2) concentrations of exchangeable bases, (3) cation exchangeable capacity (CEC), and (4) soil pH of forests in the Tamagawa basin, Japan. We defined the road ratio as level of urbanization. Study sites were located in areas with varying levels of surrounding urbanization. Surface soil concentration of exchangeable bases (especially calcium and magnesium), percent base saturation, and pH (H2O) increased with an increasing road ratio; in other words, with increased urbanization, C and CEC were unrelated to road ratio. One reason for the observation of increasing exchangeable bases with increasing urbanization appears to be the deposition of dust. The increase in exchangeable bases concentration (and % base saturation) corresponds to increases in soil pH.